The student is making wishful thinking.
In wishful thinking, the person thinks or wishes only good rather than facing reality. Wishful thinking allows person to believe what might be pleasing to believe, rather than on evidence, or reality.
Now, talking about the above student, he has been playing everyday and having fun. His exams will be held in the next week, and instead of reading and preparing for exams, he is convincing himself that he will score well in the exams. It is his false belief that he will pass the exams as he hasn't prepared yet for it.